Why is DNA copying essential in reproduction? How does it lead to variation, and why is variation useful?

1. 1 · Define in one line. DNA copying is the making of a copy of a cell's DNA before the cell divides.
2. 2 · Why it is essential. DNA carries the information for body design; copying passes this design to the new cell.
3. 3 · How variation arises. Copying is not fully accurate, so small changes appear; sexual reproduction also mixes DNA from two parents.
4. 4 · Why variation is useful. When the surroundings change, for example water becoming hot, some variants survive, so the species does not die out.
5. 5 · Link to daily life. Children of the same parents look alike but are never exactly the same.
6. 6 · Close in one line. Consistent copying keeps the body design; variation keeps the species going.

Scoring tip: Use the bacteria-in-hot-water example; it shows the value of variation in one line.